For various reasons, including cost and performance, efforts at reducing the size of electronic devices, circuits, and systems is ongoing. The goal of one such area of current active effort, micro-electro-mechanical systems (MEMS), is to reduce the size of various electronic components as well as electromechanical devices used in conjunction with those electronic components. Techniques used in creating micro-electro-mechanical systems merge the processes used in fabricating the electronic and the mechanical components. A simplification in construction, as well as a cost savings, is obtained thereby. Micro-electro-mechanical systems structures are capable of motion and/or applying force and have been used in a wide variety of applications because they provide advantages in performance, cost, reliability, and small size.
Physical size can be very important in the performance of electronic devices such as radio frequency (RF) or microwave components wherein size relative to wavelength can influence parameters such as skin depth, parasitic inductance and capacitance, transmission line behavior, and radiation characteristics. Various micro-electro-mechanical systems include switches, varactors, inductors, and resonators and have been fabricated using MEMS technology.
As is known to one skilled in the art, a varactor is a device whose capacitance varies in relation to an applied voltage. Varactors can be important elements in various high-frequency and radio frequency electronic circuits such as variable-frequency oscillators, tuned amplifiers, parametric amplifiers, phase shifters, equalizers, and impedance-matching circuits. A change in capacitance can be effected by forcing a change in the distance or effective distance (as in a reversed biased p-n junction) between the plates of a capacitor in response to a change in a bias voltage applied between the two plates.